Large, busy airports often include a control tower and staffed with air traffic controllers. Some airports are so busy the air traffic control is maintained 24-hours a day, and seven days a week. But some control towers are closed at night. Other airports are so small, or used so infrequently, that there never was a control tower installed so there never are any air traffic controllers on-hand.
At a minimum, pilots flying in or out of airports need to know about other traffic in the area, runways to use, taxi instructions, weather, crosswind advisories, etc. When there is no control tower or staff, pilots must depend on their own sight and hearing, and then self-separate using the Common Traffic Airport Frequency (CTAF) radio channel.
Gary Simon, et al., describe an automated air-traffic advisory system and method in U.S. Pat. No. 6,380,869 B1, issued Apr. 30, 2002. Such system automatically provides weather and traffic advisories to pilots in an area. An airspace model constantly updates records for a computer processor that issues advisory messages based on hazard criteria, guidelines, airport procedures, etc. The computer processor is connected to a voice synthesizer that allows the pilot information to be verbally transmitted over the CTAF-channel.
Kim O'Neil for Advanced Aviation Technology, Ltd., wrote that there are significant opportunities to improve communication, navigation and surveillance services at Scatsta Aerodrome in the Shetland Islands and in helicopter operations in the North Sea, including approaches to offshore installations. See, http://www.aatl.net/publications/northsea.htm. These improvements can allegedly lead to radical improvements in safety, efficiency and reductions in costs. A key element in achieving these improvements, according to O'Neil, is the full adoption of satellite navigation and data link services and in particular ADS-B. Various forms of VHF and other frequency data links make these improvements possible, and they provide major cost/benefits over existing costs and services. O'Neil says it is time to upgrade existing procedural services to a level more in line with modern aircraft operations. Current procedures, methods and operating practices are expensive, inefficient and adversely affect the commercial operation of air transportation services. Satellite navigation can significantly improve operating procedures, reduce decision heights at airports and improve routes and holding patterns. These all lead to corresponding gains in safety, efficiency and cost reduction. ADS-B messages also provide a communication infrastructure on which many other services can be built at low cost.
Additional services suggested by the prior art include: Airline Operational Communications for aircraft operations efficiency, maintenance and engine performance for improving flight safety, Flight Watch, automated ATIS and related meteorological services, differential GPS corrections and integrity data for improved navigation and flight safety, asset management, emergency and disaster management and coordination, remote monitoring and many other functions. The publication of RTCA MASPS and MOPS, ICAO SARPs, EUROCAE MOPS and American and European Standards for data link and ADS-B, indicates that these technologies can be introduced and certified for many beneficial and cost/effective operational services.